The present invention relates generally to the removal of organic compounds and inorganic ions from soils, hazardous spills, and aqueous environments and to the use of this polymer as an adhesive to affix an ion exchanger to remove inorganic compounds. More particularly, this invention pertains to a technology for reducing runoff and/or leaching of organic compounds such as pesticides present in an agricultural, environmental or industrial setting.
In preferred embodiments, compositions and methods are disclosed for stabilized organic polymer formulations capable of binding organic compounds, such as insecticides, herbicides, fungicides and nematicides. Also provided are methods of using such compounds in the remediation of environmental contamination, in the reduction of pesticide leaching from soil, in the containment of such pollutants, as an amendment to soil and method of coating sand particles with other particles to impart ion exchange characteristics, water holding, and plant growth enhancement capacities without reduction of soil percolation rate.
Water pollution remains a major concern although numerous substances and methods exist for its prevention or reduction. Contamination of the groundwater also can occur thus containment of the pollutants at their source is a goal. Conventional water treatment involves collection of wastewater in a central plant to be processed. This treatment mandates constant maintenance and monitoring by knowledgeable persons in the field. In U.S. Pat. No. 4,971,698 to Weber et al., biodegradable contaminants in wastewater are removed by a decentralized process dependent on microorganisms or products thereof. This method may be economically feasible for containing compounds at the source, but because of its dependence on the viability of the microorganisms it may require reapplication and its usefulness may be limited to specific biodegradable compounds.
A. Landfill Leachate Treatment
Microbes in landfills tend to produce a large amount of organic acids due in large part to anaerobic metabolism. Organic acids can complex with metal ions thereby mobilizing the metals and protecting them from oxidation which may result in precipitation from solution. This association of organic acids and inorganic materials is referred to as landfill leachate. Other pollutants that comprise landfill leachate include pathogenic organisms, solvents, pesticides, hazardous wastes, and industrial and wastewater.
Studies relating to the extent to which leachate leaves a landfill location by groundwater or surface water have shown that in arid and semiarid climate sites the water transport rates are slow, however, for sites in temperate climate the leaching happens fast, presenting a serious environmental concern. This landfill leachate contamination of aquifer and groundwater continues despite landfill construction and design criteria to minimize it.
Lining landfills with impermeable membranes has also been considered wherein leachate is collected and treated either on or off-site. Off-site treatment may involve piping the leachate to a nearby sewer system, and combining it with the municipal sanitary sewage. This off-site treatment methodology, not only requires a municipal treatment facility capable of processing the leachate loadings but also a small concentration of leachate to wastewater for effective processing. For large landfill operations, on-site treatment of leachate with package plants has been attempted; but with limited success.
In U.S. Pat. No. 4,995,969 to LaVigne describes an on-site leachate treatment method in which the leachate is forced to run through leachate-tolerant plants and microorganisms that are capable of metabolizing organic carbon compounds and adsorbing heavy metals within the leachate. Although economical and effective, it may require substantial time and experimentation to establish the ecosystem in any given landfill. As materials in the landfill change, time to adjust the ecosystem may be necessary and such time may allow an inordinate amount of leachate to escape into the environment. Also, some landfills may not be able to support the growth of the necessary organisms.
Oxidation ponds or lagoons for treating leachate tend to be unsightly, malodorous, relatively slow, require large land areas and are a breeding ground for mosquitoes.
B. Adsorbents
One method of removing organic compounds from the environment has been through adsorbents which are generally solid phase materials having very high surface area-to-weight ratios and which have the ability to concentrate adsorbates on their surfaces (U.S. Pat. No. 4,147,624). Inorganic adsorbents include activated carbon, silica, silicates, alumina natural, and synthetic zeolites and clays.
Solid phase extraction (SPE) has been used in analytical chemistry to extract, purify, and concentrate analytes such as pollutants from large volume samples such as environmental water. Also, SPE""s are used as a chromatographic matrix for the separation of mixtures whose components have different polarities.
The most common SPE material is octadecyl silica (C18 silica) although, for some applications, C8, C6, C4, C2 silica are also available. C18 silica is composed of pure silicon dioxide grains with surface silanol groups that are reacted with trichlorosilyloctadecyl groups. The result is 18 carbon chains bound to the silica. The resultant material is known as reverse phase (i.e., non-polar) silica.
When water containing relatively non-polar contaminants are passed through this material, the hydrophobic components associate with the C18 surface and the bulk of the water passes through to waste. In analytical work the contaminants are then eluted from the SPE via a solvent less polar than water.
In reverse phase chromatography, a solvent gradient from more to less polar is often used to selectively elute the different components.
The efficiency of the removal of contaminants from water by C18 silica is a function of the relative affinity of the component for the C18 hydrocarbon versus water. Thus somewhat polar compounds are not very effectively removed by C18 silica.
Importantly, the system that maximizes retention on the C18 matrix would include an extremely hydrophobic analyte dispersed in an extremely polar solvent (e.g., pure water). Solutes of intermediate polarity will be sorbed to a lesser extent by C18 silica.
The adsorption of non-polar compounds within an aqueous matrix by the C18 coated surface of the silica is preceded by the wetting of the SPE by the aqueous sample. Due to the hydrophobic nature of the C18 coating the SPE surface is quite water repellent. This inherent hydrophobiciy must be overcome before the C18 surface can efficiently adsorb the compounds of interest.
Many methods have been developed to circumvent this problem of surface wetting. Among these are the prewetting of the C18 coated silica with a solvent, such as methanol, which is miscible in both the C18 surface and water. The aqueous sample is then applied to the prewetted SPE.
Older SPE""s used minimal C18 loading on the silica surface. This allowed the residual (highly polar) silanol groups on the silica surface to Interact with the aqueous lad sample. Other examples include using a C3 spacer onto silica (via silanol) to which a proprietary polar group is attached, then a C8 chain is added; an unspecified reverse phase coating on silica; a C6 hexyvphenyl on silica, only reverse phase.
In an attempt to circumvent the inherent hydrophobicity associated with a highly non-polar stationary phase, the synthesis of mixed mode solid phase sorbents has become the current technology. Typically, the mixed mode SPE polymers contains both hydrophilic and hydrophobic moieties. In this mixed mode arrangement, the small hydrophilic moiety merely allows the polymer surface (i.e. divinylbenzene, styrene, etc.) to be water-wetted. The non-polar moiety is still the only component responsible for the actual adsorption of the pollutant. Thus the xe2x80x9chydrophobicityxe2x80x9d of the non-polar moiety is critical.
Solutes of Intermediate polarity would be maximally sorbed to the present invention via the polyoxyether/R. The polyether which can be MPEG (methyl PEG), EPEG (ethyl PEG), propyl PEG, butyl PEG, ethyl PEG/PPG for example C sub 1 to C sub 21 for example, or other number of hydrocarbons acts as a more polar stationary phase than the C18 referred to in the prior explanation on SPE""s. The polarity is further modified via the hydrophobic Rxe2x80x2 and Rxe2x80x3 (alkyl groups). Thus, the polarity of the present invention can be fine-tuned to exhibit any desired polarity.
In summary, the extent of sorption by any stationary phase is a function of the polarity of the stationary phase, the polarity of the solute, and the polarity of the solvent.
Also known in the art is that organic material can be bound to the surface of a porous support material. In U.S. Pat. No. 5,922,449 to Revis a bonded phase material useful with a chromatographic separation process includes a silanol bearing porous material, a stoiciometric amount of interactive silanes which provide the porous material with a gradient of functionality of varied polarity and not obtainable by separate interactive silanes. In Revis, the reaction of the organic moieties with the silanol groups on the surface of the silica is random as is the proximity of different organic groups to one another. Also, the silicon ether bond which connects the organic moiety to the surface of the silica has lower bond energy (less stable) than a carbon ether bond. The reagents used to generate the silica based invention (organo-chlorosilanes) are corrosive and toxic, expensive, and the resulting silica could not be used as an adhesive for other chemically active particles.
Carbon or bone char impregnated with activated carbon have been widely used to remove contaminants from aqueous systems. Not all grades perform well in all uses and the more effective grades tend to be rather expensive. Likewise, mineral-based adsorbents have not performed well in aqueous systems.
Mineral substrates such as sepiolite, attapulgite and smectites may be modified to obtain a more organophilic surface to be effective adsorbents for certain uses, however, a relatively high surface area and a cationic exchange capacity above is required (U.S. Pat. No. 4,444,665). Unfortunately, in their naturally occurring state, many of these clay minerals (aluminosilicates) swell or slake in aqueous systems resulting in gel formation or colloidal dispersions that are extremely difficult to separate from the liquid. Likewise, granular forms of these clays in naturally occurring state are useless since they simply fall apart in aqueous media.
Surface modification of minerals has been demonstrated, but the majority of these compositions require swelling or gelling-grade clays, e.g., montmorillonite, bentonite, hectorite, attapulgite, sepiolite and other smectites, in order to be useful for adsorption of organic compounds (Cowan et al., 1969). Difficulties in handling these materials, however, preclude their use in large-scale treatment of organic compounds.
U.S. Pat. No. 4,167,481 to Cremers et al. discloses effective removal of metal cations from wastewater but the process requires addition of polyamines and the presence of a cation exchanger such as natural bentonites, montmorillonites and zeolites.
Unmodified, heat-treated attapulgite has been used in water treatment to remove certain metal cations, hormones, toxins, viral micro-organisms and pesticides. Reference is made to the following U.S. Patents to Sawyer: U.S. Pat. Nos. 4,054,515, 4,116,825; 4,116,826; 4,116,827; 4,116,828. A specially processed form of heat-treated attapulgite is disclosed as a filter aid in U.S. Pat. Re. No. 25,464 (Oct. 15, 1963) of U.S. Pat. No. 3,080,214. A method of preparing heat-treated, socalled xe2x80x9cactivatedxe2x80x9d attapulgite which is substantially non-gelling and non-slaking is disclosed in U.S. Pat. No. 3,041,238 to Allegrini. These compounds, however, are unsuitable for the removal of compounds from agricultural and industrial applications which are exposed to aqueous solutions and in applications where such clays and formulations are either prohibitively expensive, or produce undesirable by products such as slaking or gelling end products. For example, such compounds are not useful in soil strata such as golf course greens where a high degree of percolativity is required and where the addition of such products would compromise the percolation and drainage of these soils.
C. Deficiencies in the Prior Art
A number of compositions and methods have been developed to remove or reduce the concentration of organic compounds from the environment. Each has one or more shortcomings that renders it unsuitable for use in certain agricultural and industrial processes, e.g. an inability to maintain particle size and integrity when contacted with aqueous environments, instability, result in foaming, are too soluble, too viscous for easy and timely application, too sensitive to high pH conditions, have diminished range of adsorbable compounds due to structural restrictions, are not easily wettable, are either prohibitively expensive, or unsuitable for application in areas where such particle size maintenance and percolation factors are critical. Water holding enhancement and cation exchange capacities are also beneficial but are lacking in present methods and compositions. Improvements in timed-release, or controlled-release agricultural products which are biofriendly are also needed. It would also be helpful if agronomic factors such as plant growth enhancement occurred which would be particularly beneficial in the preferred embodiment of use on golf courses.
The present invention overcomes these and other shortcomings in the prior art by providing compositions and methods for the highly stable salvation and adsorption of organic compounds, for imparting ion exchange and water holding capacities to the soil profile without reduction of percolation rate, for the removal of organic contaminants (such as pesticides) from agricultural and commercial environs, and nutrient retention capacity for enhancement of plant growth, e.g. grass. Also provided are devices and apparatus for the remediation of organic wastes in situ and in solution using reactive barriers, flow through filtration systems, and organic waste containment facilities. In certain embodiments, compositions are provided for the reduction of pesticide leaching from athletic facilities, and in particular, golf course greens, and athletic turfs.
The invention discloses and claims a solid phase mixed solvent (SPMS) polymer, a polyoxyethylene diether, comprising monoalkyl PEG or PEG/PPG ether of the methylolated dialkyl diphenol. Preferably, the methylolated monoalkyl PEG/PPG dialkyl diphenol is crosslinked via the methylol groups within a phenol-formaldehyde (PF) resole. A monolalkyl ether of PEG/PPG is reacted with phosphorous tribromide to form monoalkyl PEG/PPG bromide which is reacted with the methylolated dialkyldiphenol via the Williamson ether synthesis thus forming the monoalkyl PEG/PPG ether of the methylolated dialkyl diphenol (the SPMS polymer). See FIGS. 1A and 1B. The Williamson ether synthesis was used because it was found that no reaction occurred when PEG, an alcohol was added to a phenolic resole and the resultant mixture was cured at 180xc2x0 C., i.e. no cross-linking occurred. Methylol, a hydroxyl bound to a carbon located alpha to a phonolic ring is required for cross-linking. Potentially, another type of crosslink could occur via a dual Williamson starting with a dihydroxy PEG. With the present invention it is the ether group that provides the polar character.
The SPMS polymer may be utilized directly, or coated or bound to a matrix or a substrate. Preferably, the polymer is capable of binding an organic compound, and in particular, organic contaminants, fertilizers, and pesticides including insecticides, a herbicides, a fungicides, or a nematicides. The polymer may be utilized within an agricultural site as a reactive containment barrier or a hazardous spill cleanup device or apparatus. (FIG. 12A) The polymer may also be formulated into a filter, sedimentation tank, or water treatment device. (FIG. 12B) The polymer may be Incorporated into a soil amendment, additive, hazardous spill barrier or containment means. The polymer may also be formulated for use in a device or system for treating water, soil, sewage, wastewater, or agricultural leachate, or for removing organic pollutants from a solution.
Alternatively, the SPMS polymer compositions may be comprised with a system for removing pesticides from a leachate or contaminated solution. The system generally comprises at least one leachate or contaminated water supply source, with at least one inlet port into which the SPMS polymer composition is placed and into which the leachate supply source flows to contact the leachate with the SPMS polymer composition, and at least one outlet port, and flow control means for draining the treated leachate from the treatment basin. (FIG. 13) The system may also comprise a continuous flow system or a batch processing system.
The invention also discloses and claims a method of preparing a SPMS polymer composition that has the desired property of being able to adsorb one or more organic compounds onto the polymer. The method generally involves coating, spraying, aerosolizing, or otherwise contacting a suitable matrix with the SPMS polymer composition under conditions effective to permit coating of the matrix with the composition.
A method of preparing a golf course to prevent leaching of a pesticide from the course and which enhances water holding capacity and plant growth is also provided by the invention which generally involves amending one or more layers of soil underneath the golf course grass with one or more SPMS polymer compositions. The composition may be applied to discrete layers under the athletic turf, alternatively may be mixed throughout the soil underneath the grass, or applied as a top dressing. See FIGS. 15A and 15B.
In a first embodiment, the present invention concerns solid phase mixed solvent polymers (SPMS polymers) that are capable of binding to organic compounds and preventing the leaching of such organic compositions from the area in which the SPMS polymers are located. The SPMS polymer of the present invention may be prepared so that they bind either polar or non-polar organic compounds, or alternatively, may be designed such that a single SPMS polymer, or a combination of two or more distinct SPMS polymers may bind both polar and non polar compounds. The ability of SPMS polymers to bind more than one type of organic compound makes them useful for a variety of organic chemical remediabon situations. A given SPMS molecule can be designed to adsorb a range of organic compounds based upon their range of polarity and charge density. This range extends from the intermediate polarity compounds which are soluble in the polyether to the non-polar alkyl groups at the other end of this range. Non-polar compounds soluble in hydrocarbons comprise this end of the range. In Bouvier U.S. Pat. No. 6,254,780, hydrophobicity is critical in that only the hydrophobic divinylbenzene (DVB) actually adsorbs the solute while the hydrophilic pyrolidone merely facilitates water wetting of the DVB surface. In contrast, the polyoxyether (polar moiety) of the present invention actually participates in the adsorption of the solute pollutant synergistically with the alkyl groups. The ""780 patent teaches the use of a small hydrophilic moiety bound to the hydrophobic polymer matrix. The hydrophobic polymer is the site of adsorption of the pollutant The hydrophilic moiety merely facilitates the water-wetting of the polymer surface. The polyoxyether and the alkyl groups are configured on the final polymer in a format which is stereochemically favorable to their mutual interaction with the pollutant. The optimum sorption of a compound by the polymer is determined by the ratio of polyoxyether to alkyl groups as well as the distribution of charge on the pollutant molecule.
A mixture of SPMS""s would extend the range of sorbable compounds although less capacity for a specific compound as compared to a xe2x80x9cpurexe2x80x9d SPMS polymer which has been optimized for that specific compound would be expected.
In a preferred embodiment, the SPMS polymer is a dialkyldiphenol-polyethylene glycol polymer. The ranges of polarity associated with the PEG and alkyl moieties translates into a wide range of solutes adsorbed. The steriochemical proximity of the polyoxyether moiety and the alkyl moiety is easily controlled and facilitates their synergistic solvation of the compounds of interest. Other advantages of the polymer of the present invention include the ease of synthesis, non-phytotoxic characteristic, excellent stability, and it is relatively inexpensive to make. MPEG (methoxy PEG) and other alkyl-PEG ethers and PEG derivatives including but not limited to PEG/PPG ethers and esters and PEG esters and ethers of various molecular weights, (6000, 7000, about 8000, about 9000 or greater) can be employed in the formulation of the PSMS of interest. MPEGs such as those with average molecular weights, eg. about 5000, however, are preferred for adsorption of many pesticides. In certain embodiments, the inventor contemplates the beneficial use of smaller molecular weight MPEGs, eg. from about 500 to about 4000 for the remediation and adsorption of certain organic compounds and may be useful in certain embodiments. Likewise, when preparing SPMS polymer compositions for the adsorption of multiple types of organic compounds, it may be desirable to prepare the SPMS using more than one PEG, e.g. different-sized MPEGs as starting materials, two or three different sized PEGs being preferable if more than one PEG is to be utilized.
Although formaldehyde is used as an illustration herein, it is contemplated that other low-molecular weight aldehydes including acetaldehyde, propionaldehyde, or butaraldehyde, may be substituted in creating derivative SPMS polymer formulations that may be desirable for certain applications of the polymer composition.
Preferably the phenol is at least a technical grade phenol, although any grade phenol may be used so long as the phenol does not contain trace impurities that would alter or inhibit the proper polymerization of the compound. Alternatively, the phenol component used in the preparation of the phenol- aldehyde (or formaldehyde) (PF) compound may include but is not limited to one or more of the following phenol derivatives: 1-hydroxyphenol, 2-hydroxyphenol, 3-hydroxyphenol, 1,2-dihydroxyphenol 1,3-dihydroxyphenol, 1,4-dihydroxyphenol, lignin and the like. In an illustrative embodiment, the phenol:formaldehyde component of the SPMS polymer was a PF resole (Cascophen SPxe2x80x947550K, PF Resin, Bordon Chemical, Louisville, Ky.).
The adsorbent properties of the dialkyl diphenol polyoxyether (a telechelic molecule) crosslinked to a phenol-formaldehyde (PF) matrix (resole) permit their direct use in binding organic compounds, without the need of coating the compound onto a substrate. A telechelic molecule is a pre-polymer capable of entering into further polymerization through reacting terminal functional groups. The SPMS polymer compound is readily formulated for coatng, crosslinking, absorbing, or binding to a solid substrate or a matrix. This matrix or substrate may provide support or impart other physical properties to the SPMS polymer compound that facilitate its use in a variety of practical applications.
In another embodiment, the substrate upon which the SPMS polymer is coated is a sand, sea sand, or a mineral such as silicate. Formulations of the PF-PEG SPMS polymer coated onto sand particles are particularly preferred for use in the preparation of athletic turfs, such as golf courses, and the like, where maintaining the percolativity of the soil is important. These sand-SPMS polymer formulations are also desirable for amendment to agricultural soils, and to other environmental sites where location of the SPMS polymer for the purpose of adsorbing organic compounds is desirable.
In further embodiments, it may be desirable to apply the adsorbent to a substrate or matrix having a larger particle or mesh size than a granular substrate such as sand. In these instances, the SPMS polymer compositions may be formulated for application to rock, gravel, pebbles, clay, expanded clay, silica gels, zeolites, or metals (including metal filings, shaving, pellets, beads, turnings, etc.). Alternatively, the matrices may be a synthetic compounds such as plastics (e.g., polystyrenes, polyethylenes, polypropylenes, polybutalenes, nylon, rayon, dacron, ordon, etc.) or other monomeric or polymeric resins and the like. The SPMS polymer composition may also be applied to substrates such as beads, glass, glass fibers, fabrics, ceramics, fiber filters, spun fibers, and even onto a substrate of plant-derived or extractable material, e.g. cellulose fibers, lignins, etc. Virtually any solid or semi-solid support, matrix, or substrate or mixtures of these substrates is envisioned to be useful in the creation of SPMS polymer-formulations where it is desirable to impart the adsorptive capabilities of the polymer to a target surface. Because the SPMS polymer compositions, in the broadest sense, are used to adsorb organic compounds, they may also be used to form part of an apparatus or a device that is intended to remove or reduce the concentration of organic compounds from an environment or a contaminated site, solution, or water source. For example, in one preferred embodiment, a SPMS polymer composition may be added to the soil in or around a sports facility, agricultural, commercial industrial or residential turf or field, In a preferred embodiment, the SPMS polymer composition may be added to the soil or coated onto or integrated with sand for application to a subsurface layer of a golf course green.
In another embodiment, the SPMS polymer composition may comprise part of a water filter, a water treatment facility, a sediment filter, or a reactive barrier. As such, the compositions may be used to adsorb organic contaminants from a groundwater source, or a municipal water supply, or may be placed in the ground as a barrier to prevent leaching or seepage of contaminated water into a given area, or to prevent or reduce the amount of contaminant moving through the ground from one site to another.
Because of the widespread use of organic compounds (and particularly organic pesticides), the entrance and contamination of environmental soils, sites, and particularly water sources, is nearly inevitable. Many types of organic compounds may be introduced into the environmental, e.g. pesticides such as herbicides, rodenticides, insecticides, fungicides, microbicides, and nematicides. The application of pesticides to a target area may be contained through the use of the SPMS polymer compositions disclosed herein. For example, in one embodiment a SPMS polymer-sand adsorbent amendment was used to reduce or contain the migration of the nematicide, fenamiphos, and its metabolites, through the soil layers under a golf course green.
Organic compound spills, including pesticides, are a common occurrence. In such instances, the application or introduction of one or more SPMS polymer compositions to the affected area may be used to adsorb or contain such an organic spill. For non agricultural uses, the SPMS polymer composition may be applied directly to the contaminated site. After adsorption the resulting SPMS polymer-pollutant may be thermally oxidized, the result would be sand and CO2. Thermal oxidation is currently used to decontaminate soil. After application to the spill, the SPMS polymer composition containing the adsorbed contaminant(s) may conveniently be collected or alternatively, the contaminant may be desorbed from the polymer and disposed of.
Alternatively, a SPMS polymer composition may be used to form a barrier at a perimeter around the spill. Of course, the barrier does not need to encircle the spill, but rather may be placed at a location in the general direction of migration of the spill so that it may be contained by the adsorbent or may be placed as a barrier at a location as preventive measure.
A common use of pesticides is in the maintenance of sports facilities. Sports facilities include, but are not limited to, golf, tennis, croquet, polo, horseracing, football, baseball, soccer, or cricket. A SPMS polymer composition may be added to the soil of the facility or may be a component of a drainage treatment system that collects wastewater, runoff, or leachate from the sports facility. Altematively, the composition may be mixed or layered underneath the sod preferably as an amendment to the soil, such as a golf course green, In such a manner as to prevent pesticide leaching.
As a component of a golf course, it is important that the SPMS polymer composition maintain a high rate of percolativity or conductivity, be placed in a location to efficiently bind the pesticides applied to the course, and prematurely adsorb or inactivate the pesticide before its role is accomplished in the soil. One use of the SPMS polymer composition is as an amendment to one or more of the subterranean support structure layers of the golf course, particularly a green. These support structure layers include the gravel drainage blanket, intermediate layers, and the root zone layer. A sublayer of SPMS polymer-treated soil (for example, see FIG. 7B) can be added as a discrete layer beneath the sod layer In one or more of the subsurface, or subterranean, layers.
When mixed throughout the soil, an SPMS polymer composition may be effective at a range of ratios. The ratio of SPMS polymer composition to non-SPMS polymer compositions is about 1:0 to about 1:40, by weight, the preferred ratio being about 1:20 by weight. After mixing the clay with the sand/resole the clay coated sand is thermoset. The finished product is then added to sand, preferably plain quartz sand, in the ratio of about 25% SPMS to about 75% quartz sand and blended throughout the soil during construct of a golf green, or other facility, or may be added to the soil at a later date by, for example, tilling, injection (pressure), topdressing, backfilling holes introduced into the soil surface by, for example, aerification, and as off-site premix which is used for golf course construction. The SPMS polymer may be added to form one or more discrete layers within the soil. It is believed that, since the binding of pesticide to the polymer is not 100% or irreversible, it may be advantageous to place the SPMS polymer within the rootzone.
The aqueous microenvironment associated with the surface of the polymer particle contains some concentration of pesticide. This concentration is controlled by the partition co-efficient of the pesticide in water/polymer. This can be manipulated via the polymer formulation. The concentration of pesticide in the microenvironment is great enough to maintain efficacy of the pesticide with the excess pesticide residing on the polymer replenishing that removed by leaching and microbial degradation. Thus extending the efficacy of the pesticide by prolonging its existence within the soil. In preferred embodiments, the percentage of SPMS polymer composition comprising a discrete layer is such that it binds nearly all of the applied organic compound and maintains the hydraulic conductivity of the soil.
It is contemplated that the accumulation of the organic compound within the SPMS polymer-comprising layer or composition may serve to enhance microbial degradation of the organic compound. As such, the formulation of the invention may be used to enhance microbial colonization of an area where SPMS polymer is present. If the organic compound is a preferred substrate for a particular microbial organism. The extended presence of the compound in the soil due to the SPMS polymer sorbtion will favor the colonization of the soil by these microorganisms The adsorbed compound, however, may be less available to the microbes as compared to the same compound in solution.
Because the SPMS polymer compounds may be affixed to substrates of different particle sizes and compositions, SPMS polymer composition may improve the overall nature or character of the soil, as well as provide organic leachate adsorption. A SPMS polymer composition may be added to the soil to adsorb organic compounds in the soil or to alter the percolativity, consistency or integrity of the soil. It is common practice to add compounds to soils to improve the ability of these soils to support plant growth. The SPMS polymer compositions may not only provide organic adsorption, but may in fact improve the overall quality and retain nutrients in the soil to which it is added thus enhancing growth.
The use of the SPMS polymer as an adhesive for the binding of clay to the surface of a substrate circumvents the adverse effects of clay in soils (e.g., reduced percolativity) while preserving the beneficial ion exchange behavior of the clay. Ion exchange is a mechanism by which fertilizer cations and anions are retained within the exchanger then released slowly to the roots thus preventing a flush of nutrients into the groundwater subsequent to fertilization.
Also, clays swell when exposed to water, which occlude soil pores and reduce percolation. The clay bound to the sand surface by the polymer does not clog soil pores. The water associated with the swollen clay remains plant available. The polymer coated sand allows for greater water holding capacity than occurs in uncoated sand and thus plants show far less drought stress as compared with plants grown under similar conditions in uncoated sand.
As an alternative to or in addition to soil amendments, an SPMS polymer composition may comprise a filter that is operatively connected to the drainage system of a golf green (FIG. 6). A simple filter system is taught in U.S. Pat. No. 5,685,981. Filters generally have an intake port, a chamber, and an outlet port. In preferred embodiments, the chamber comprises an SPMS polymer composition such that organic compounds within aqueous solutions are bound by the SPMS polymer composition and prevented from flowing through the outlet port thereby purifying the aqueous solution. The composition may be supported by a matrix such as sand, beads, fiber, etc., comprised within a filter cartridge, or, alternatively, coated on the chamber walls itself.
The present invention is also useable in the removal of organic compounds from aqueous solutions, eg. water, wastewater, sewage, leachate, groundwater, or industrial runoff. In preferred embodiments, the aqueous solution is leachate. One method of removing organic compounds from an aqueous solution is by use of a water treatment system. A water treatment system may be a simple column filter or a complex municipal water treatment facility.
The water systems commonly used by municipal water treatment facilities include sequence batch biological reactor, continuous activated sludge, trickling filter, aerated lagoon, and anaerobic filter. The aqueous solution may be treated by flowing through a column comprising an SPMS polymer composition or by contacting the aqueous solution with particles comprising SPMS polymer composition in a batch method. In the batch method, particles comprising an SPMS polymer composition are added to a water sample suspected of containing one or more organic compounds, mixed to provide sufficient contact between the particles and the organic compounds to allow binding, and then separated from the newly purified aqueous solution. Separation may be by means of gravity, centrifugation, magnetism, or filtration through a size-selective porous membrane, or a mesh filter, or other size-exclusionary grating, grid, etc.